I was waiting for someone on Gesneriphiles to answer your question but since I am here I will say something. I have never been sure just what kind of light brings out variegation or greens up a plant. But, as a general rule, I do believe and have seen the effect that temperature has on variegation. For true variegated plants, that is--plants that have mutated to be variegated, cool temperatures increase the amount of variegation. On AV's this is well known. In a warm room, and under lights, they will green up, if variegated. Once I put a Streptocarpella 'Blueberry Cream' in my downstairs cool section of my greenhouse, and the plant turned so variegated that it had hardly any green on the leaves at all--yet it was healthy.

On plants like Chirita sinensis, which has a marbled pattern of natural variegation, I have never known what brings out really good variegation. On the Gesneriad Reference Web are some photos of show plants, mostly grown in the Toronto area, that have much more pattern than I get. My guess is that they were grown under lights, grew to large mature specimens, and were not overly warm. But, that's just a guess. To see what I mean, look them up on GRW--sinensis, s. latifolia, 'Hisako', 'Betty'.

Jon

Here is a link that might be useful: GRW